ASTM D2427 Method for Determination of C2 through C5 Hydrocarbons in Gasolines
ASTM D2427 Standard Test Method for Determination of C2 through C5 Hydrocarbons in Gasolines by Gas Chromatography
5. Apparatus
5.1 Chromatograph - Any chromatograph having a thermostated oven and a detection system of adequate sensitivity may be used. The detection system must have sufficient sensitivity to produce a recorder deflection of at least 5 mm for 0.1 liquid volume percent of pentene-1 in the sample or synthetic blend being analyzed.
NOTE 1 - If the sensitivity of a given system is inadequate, it can be increased by using a more sensitive recorder or detector, or by using more sample if the resolution is substantially unaffected.
5.2 Recorder - A 1 to 10-mV recorder with a full-scale response time of 2 s or less and a noise level no greater than more or less 0.3 % of full scale.
5.3 Columns:
5.3.1 A description of columns and valving arrangements that meet the requirements of this method are described in Annex A1. Persons using other column materials must establish that the column gives results that meet the precision requirements of Section 10.
5.3.2 Analyzer Column - The column system used must be capable of resolving the individual C2 to C5 paraffins and olefins well enough so that the individual hydrocarbons listed in Section 1 may be reported. The resolution should be such that at the operating conditions selected, the distance from the base line in the valley between two peaks representing compounds reported is not greater than 50 % of the height of the smaller peak. If an internal standard is used, it must be completely resolved from the other components.
5.3.3 Precut Column - This column must be capable of separating the C5 and lighter olefins and paraffins from the C6 and heavier olefins and paraffins. The resolution should be such that at the operating conditions selected, the distance from the base line to the valley between 2-methylbutene-2 and 2,2-dimethylbutane is not greater than 50% of the height of the smaller peak. If an internal standard is used, it must be eluted with the C5 and lighter materials.
6. Reagents and Materials
6.1 Compounds for calibration shall be of a purity of not less than 99 mole %. Calibrants should include compounds 1.1.5-1.1.16 as listed in Section 1. The concentration of ethylene, ethane, propylene, and propane is generally so low in most samples that calibration with these materials is unnecessary (Warning - Extremely flammable gas under pressure. Extremely flammable liquids.) Commercially available certified blends of light hydrocarbons may be used to establish calibration data where their compositions are applicable. If an internal standard is used to relate the concentration of light hydrocarbons to the whole sample it must be included as a calibrant.
6.2 Carrier Gas - A carrier gas appropriate to the type of detector used should be employed. Helium or hydrogen can be used with thermal conductivity detector (Warning - Compressed gas under high pressure.) (Warning - Hydrogen is extremely flammable under pressure.) Nitrogen or argon can be used with ionization or gas density detectors (Warning - Compressed gas under high pressure).
6.3 Liquid Phase - See Annex A1.
6.4 Solid Support, for use in packed column; usually crushed firebrick or diatomaceous earth. Mesh size should be appropriate to the system selected from the supplement.
